Office of Habitat Conservation, NOAA/National Marine Fisheries Service, Silver Spring, MD 20910.
“Fish habitat” is a
simple term. We can easily
imagine a fish languishing
under a log or in
a kelp forest, and we can
picture a school of forage
fish zipping through the
water column. We can
also grasp that the preferred
space for many species might change as the seasons change and
the years pass by. But the rest of the story is not quite so simple,
mostly because life is more complicated and knowledge is often
limited. This month’s “Fish Habitat Connections” seeks to demystify
those details so we can appreciate the intricacies in the
fish habitat world and become more emboldened to serve fish
not just as a meal but as they deserve.
Let’s begin with semantics. Each fish occupies its preferred
niche in the ecosystem. The environmental conditions of that
space define the fish’s preference at each life stage—water
temperature, depth, salinity, flow, bottom type, prey availability annual cycles, and much more. It is important for us
as professionals to place those variables in proper context so
that individual fish can survive, fish stocks can flourish, fishery
management can succeed, and society can benefit from our nation’s
That simplistic summary reflects our hopes, which are
complicated by the reality that we know very little about our
most basic habitat questions. With luck, we know where fish
live throughout their life cycles. But oft times we have few
insights into the shifting preferences of each life stage. Even
that knowledge is elusive unless we have close observations
from multidecadal stock assessments or the insights offered
by a healthy fishery. Almost universally, we rarely understand
the relationships between fish and their habitat.
If a wetland is
dredged, how will the local fish populations change over the
short and long term? If a dam is breached, will the new hydrological
regime support native species or invite invasive species?
If an acre is protected or restored, how will the population respond?
Will harvests increase?
These issues read like the final program at many an American
Fisheries Society (AFS) conference. They have vexed us
as a profession for decades. We must manage fisheries with the
best available information, scant as it might be. And we must
identify our primary needs so that gaps are addressed.
Fish Habitat Connections There is also the still-new concept of ecosystem-based approaches.
Habitat must be an essential variable in stock assessments,
but those analyses must be conducted with an ecosystem
in mind. Those perspectives can be as important as data. Without
that challenge, we won’t even know we have a data gap.
Considering how complex this simple topic can be, and
how it reflects human pressures from our coasts to the mountains,
it is probably no surprise that we continue to lose habitat
function at alarming rates. Along our oceans, marine and estuarine
wetland loss was three times higher between 2004 and
2009 than in the previous 5 years (Stedman and Dahl 2008;
Dahl 2011). Inland wetland loss is not as severe, but hundreds of
rivers representing thousands of river miles are compromised by
blockages that prevent fish movement upstream or downstream.
The first-ever national fish habitat assessment found that 53%
of our estuaries are at high or very high risk of habitat degradation
(National Fish Habitat Board 2010). Given those numbers,
it is unfortunate that those places provide vital nursery habitats
for many of our favorite fish.
As fishery professionals from all disciplines, our assignment
is to combine our skills to protect important habitats and
restore those that are degraded. Our mission will be slightly
less daunting if we and our partners can set a pace to match
the steady pressure of human population growth and looming
challenges such as climate change. AFS represents an incredible
knowledge base. If anyone can analyze our habitat knowledge,
fill our priority gaps, apply lessons learned, and improve habitats
for the benefit of all, it is us.
Next month we will shift from the nuances of semantics
to the harsh realities of the challenge before us. It is imperative
that we engage now! Economic and ecological facts urge AFS,
its units, each of us, and our home institutions to accept the challenge.
We will explain the opportunities before us and how our
collective skills are needed for success.
Dahl, T.E. 2011. Status and trends of wetlands in the conterminous
United States 2004-2009. U.S. Department of the Interior, Fish
and Wildlife Service, Washington, D.C. 108 pp.
National Fish Habitat Board. 2010. Through a fish’s eye: the status of
fish habitats in the United States 2010. Association of Fish and
Wildlife Agencies, Washington, D.C. 68 pp.
Stedman, S., and T. E. Dahl. 2008. Status and trends of wetlands in the
coastal watersheds of the Eastern United States 1998 to 2004. National
Oceanic and Atmospheric Administration, National Marine
Fisheries Service, and U.S. Department of the Interior, Fish and
Wildlife Service, Washington, D.C. 32 pp.